The long term objective of this project is the development of a rapid quantitative assay for fentanyl and a qualitative assay (screen) for fentanyl and other narcotics of the 4-anilinopiperidine series. The assay will be developed with the goal of measuring the drugs in whole blood spotted on filter paper, i.e. finger-stick assay. The proposed methodology will initially involve I125 immunoassay techniques which will be later changed to solid phase enzyme immunoassay protocol. The direct benefit to the health field will be the availability of a test which is rapid, non- labor intensive, cost-effective, and specific for the fentnayl family of drugs and detection of their abuse. The specimen employed may be obtained away from the laboratory by non- trained personnel, it cannot be adulterated and can be obtained without personal humiliation (being observed passing urine). The development of this test will make available to hospitals, doctors offices, commercial laboratories and drug screening centers the first convenient, specific method for assaying or screening for the fentanyl family of drugs and their abuse.